Eyeglass prescription method

ABSTRACT

In general, in some embodiments, the disclosure provides a method that includes making a subjective refraction of a person to determine information about the person&#39;s vision, making a wavefront measurement of one or both of the person&#39;s eyes to determine information about the optical properties of one or both of the person&#39;s eyes (e.g., aberrations), calculating a prescription for the person based on the information about the person&#39;s vision and the information about the optical properties of one or both of the person&#39;s eyes, and outputting the prescription.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119(e)(1) to U.S. Ser.No. 60/854,374, filed Oct. 25, 2006, the contents of which are herebyincorporated by reference.

FIELD

Eyeglass prescription methods, and related systems, components andarticles are disclosed.

BACKGROUND

Eye care professionals (ECPs), such as opticians, optometrists,ophthalmologists, and eye doctors, typically dispense eye glasses topeople based on a study of the person's vision that involves taking amedical history of the person's vision and a subjective refraction toget the person's prescription. After the person selects eyeglass frames,the ECP usually measures the centration of the frame for the person andorders lenses for the frame based on the person's prescription and thecentration measurement.

SUMMARY

In general, methods for dispensing eyeglasses are disclosed. The methodscan involve making a subjective refraction and an objective refractionand combine both refractions to calculate the person's prescription. Themethods may involve making a wavefront measurement of one or both of theperson's eyes and using the wavefront measurement to calculate theperson's prescription.

In general, in one aspect, the disclosure features a method thatincludes making a subjective refraction of a person to determineinformation about the person's vision, and making an objectiverefraction of the person to determine information about the person'svision. The method also includes calculating a prescription for theperson based on the information about the person's vision determined bythe subjective refraction and the objective refraction, and outputtingthe prescription.

In general, in another aspect, the disclosure features a system thatincludes an input interface configured to input information about aperson's vision determined on the basis of a subjective refraction. Thesystem also includes a device configured to get information about aperson's vision determined on the basis of an objective refraction. Thesystem further includes a calculating device configured to calculate aprescription for the person based on the information about the person'svision determined by subjective refraction and based on the informationabout the person's vision determined by objective refraction. Inaddition, the system includes an outputting interface configured tooutput the prescription.

In general, in a further aspect, the disclosure features a method thatincludes making a subjective refraction of a person to determineinformation about the person's vision. The method also includes making awavefront measurement of one or both of the person's eyes to determineinformation about the optical properties of one or both of the person'seyes. The method further includes calculating a prescription for theperson based on the information about the person's vision and theinformation about the optical properties of one or both of the person'seyes. In addition, the method includes outputting the prescription.

In general, in an additional aspect, the disclosure features a methodthat includes making a wavefront measurement of one or both of theperson's eyes to determine information about the optical properties ofone or both of the person's eyes. The method also includes calculating aprescription for the person based on the information about the opticalproperties of one or both of the person's eyes, where calculating theprescription includes ray tracing light paths through one or both of theperson's eyes based on the information about the optical properties ofone or both of the person's eyes. The method further includes outputtingthe prescription.

In general, in another aspect, the disclosure features a system thatincludes relay optics configured to collect illumination scattered froma person's eye during operation of the system. The system also includesan optical sensor configured to detect the illumination collected by therelay optics. The system further includes an electronic processorconfigured to receive information about the illumination detected by theoptical sensor and to calculate a prescription for the person based onthe information, where calculating the prescription includes ray tracinglight paths through the person's eye based on the information.

In general, in another aspect, the disclosure features a method thatincludes calculating a prescription for the person based on theinformation about a person's vision determined by a subjectiverefraction and an objective refraction.

In general, in a further aspect, the disclosure features a system thatincludes a device configured to calculate a prescription for a personbased on information about the person's vision determined by subjectiverefraction and based on information about the person's vision determinedby objective refraction. The system also includes an outputtinginterface configured to output the prescription.

In general, in a further aspect, the disclosure features a method thatincludes making a subjective refraction of a person to determineinformation about the person's vision, making a wavefront measurement ofone or both of the person's eyes to determine information about theoptical properties of one or both of the person's eyes (e.g.,aberrations), calculating a prescription for the person based on theinformation about the person's vision and the information about theoptical properties of one or both of the person's eyes, and outputtingthe prescription.

In general, in another aspect, the disclosure features a method thatincludes making a wavefront measurement of one or both of the person'seyes to determine information about the optical properties of one orboth of the person's eyes, calculating a prescription for the personbased on the information about the optical properties of one or both ofthe person's eyes (e.g., aberrations), wherein calculating theprescription includes ray tracing light paths through one or both of theperson's eyes based on the information about the optical properties ofone or both of the person's eyes (e.g., using ray tracing software), andoutputting the prescription.

In general, in still another aspect, the disclosure features a systemthat includes an input interface configured to input information about aperson's vision determined on the basis of a subjective refraction, adevice configured to get information about a person's vision determinedon the basis of an objective refraction (e.g. via a wavefront refractorsuch as a Shack-Hartmann sensor, an auto-refractor, or a tomographetc.), a calculating device, such as a personal computer or aworkstation, configured to calculate a prescription for the person basedon the information about the person's vision determined by subjectiverefraction and based on the information about the person's visiondetermined by objective refraction, and an outputting interfaceconfigured to output the prescription.

In general, in another aspect, the disclosure features a system thatincludes relay optics (e.g., imaging optics and/or interferometeroptics) configured to collect illumination scattered from a person's eyeduring operation of the system, an optical sensor (e.g., aHartmann-Shack sensor) configured to detect the illumination collectedby the relay optics, and electronic processor (e.g., a computer)configured to receive information about the illumination detected by theoptical sensor and to calculate a prescription for the person based onthe information. Calculating the prescription includes ray tracing lightpaths through the person's eye based on the information.

In general, in still another aspect, the disclosure features a systemthat includes an input interface configured to input information aboutthe person's vision determined on the basis of a subjective refractionof a person, a wavefront measurement device configured to make awavefront measurement of one or both of the person's eyes to determineinformation about the optical properties of one or both of the person'seyes, a calculating device configured to calculate a prescription forthe person based on the information about the person's vision and theinformation about the optical properties of one or both of the person'seyes; and an output interface configured to output the prescription.

Embodiments of the methods and systems can include one or more of thefollowing features.

The objective refraction may be derived from a wavefront measurement ofone or both of the person's eyes. The wavefront measurement can acquireinformation about the optical properties of one or both of the person'seyes. A wavefront measurement may be accomplished by the Shack-Hartmannmethod or the Tscherning method.

In some embodiments, the objective refraction may also be derived from aray tracing method through one or both of the person's eyes. The raytracing method can also determine information about the opticalproperties of one or both of the person's eyes. The ray tracing methodmay be a chief-ray ray tracing method or a ray bundle ray tracing methodwhereas the diameter of the bundle may have the size of the pupil of theperson's eye.

Optionally (e.g., instead of conducting a wavefront analysis or a raytracing method) objective refraction may also be derived frommeasurement of the tomography of the respective person's eyes. Thedetermination of the tomography of a person's eye can deliver in a firstthe topography of the eye and subsequently by calculation the aberrationof the eye.

The subjective refraction can include determining a value for sphere ofone or both of the person's eyes. This value for distinguishing reasonsin the following is called first value for sphere. Additionally oralternatively the objective refraction may include determining a valuefor sphere of one or both of the person's eyes. This value may differfrom the first value for sphere and therefore in the following is namedsecond value of sphere.

Consequently, calculating the prescription can include determining aprescription value for sphere of one or both of the person's eyes fromthe first value for sphere of one or both of the person's eyes and thesecond value for sphere of one or both of the person's eyes. Thisprescription value may be an average value resulting from the first andsecond values described above. Averaging may include different weighingof the first and second values. In a simple case the arithmetic averagewill be used. This prescription value may also be derived from thesecond value, whereas the second value has be within a certain range ofthe first value, otherwise it will be shifted within this range.

The subjective refraction can also include determining a first value forcylinder of one or both of the person's eyes. The objective refractioncan correspondingly include determining a second value for cylinder ofone or both of the person's eyes. Calculating the prescription cantherefore include determining a prescription value for cylinder of oneor both of the person's eyes from the first value for cylinder of one orboth of the person's eyes and/or the second value for cylinder of one orboth of the person's eyes. The wordings “first” and “second” are usedfor distinguishing reasons, only. Again, this prescription value forcylinder may be an average value resulting from the first and secondvalues described in the foregoing. Averaging again may include differentweighing of the first and second values for cylinder. This prescriptionvalue may also be derived from the second value, whereas the secondvalue has be within a certain range of the first value, otherwise itwill be shifted within this range.

In addition or as an alternative the subjective refraction can includedetermining a first value for cylinder axis of one or both of theperson's eyes. Similarly, the objective refraction can includedetermining a second value for cylinder axis of one or both of theperson's eyes. Calculating the prescription thus can include determininga prescription value for cylinder axis of one or both of the person'seyes from the first value for cylinder axis of one or both of theperson's eyes and/or the second value for cylinder axis of one or bothof the person's eyes. The prescription axis value can be an averagevalue. Alternatively, as a prescription value the first or second axisvalues can be used.

In another implementation of the methods described above calculating theprescription can include determining a prescription value for meansphere of one or both of the person's eyes from a first value for meansphere of one or both of the person's eyes as calculated from the sum ofthe first value for sphere and half of the first value for cylinder anda second initial value for mean sphere of one or both of the person'seyes as calculated from the sum of the second value for sphere and halfof the second value for cylinder.

Additionally or alternatively, the methods can be embellished such thata second value for mean sphere of one or both of the person's eyes isset to the sum of the second initial value for mean sphere for therespective eye and a predetermined plus value if the second initialvalue for mean sphere for the respective eye exceeds the predeterminedplus value and wherein the second value for mean sphere for therespective eye is set to the difference of the second initial value formean sphere for the respective eye and a predetermined minus value ifthe second initial value for mean sphere for the respective eye exceedsthe predetermined minus value. The difference of the first mean spheresbetween the two eyes and the difference of the second mean spheresbetween the two eyes can be calculated. The method may be performed suchthat the second mean spheres of the respective eyes are amended suchthat the differences between the first and second mean spheres of therespective two eyes are identical and such that the prescription valuefor mean sphere of the respective eye is set to the amended second meansphere.

A typical predetermined plus value is in the range between 0.1 and 1dpt, e.g. between 0.15 dpt and 0.75 dpt, for example 0.25 dpt. Thepredetermined minus value can be set to different values dependent onthe range of wanted addition. Exemplarily, the predetermined minus valuecan be set to: a) 0.50 dpt for a wanted addition between 0.00 dpt and1.75 dpt; b) 0.25 dpt for a wanted addition between 2.00 dpt and 2.25dpt; or c) 0.00 dpt for a wanted addition greater than 2.25 dpt

One method may include setting the prescription value for cylinder ofthe respective eye to the first value for cylinder of the respectiveeye. One method may include setting the prescription value for cylinderaxis of the respective eye to the first value for cylinder axis of therespective eye.

One of the methods referred to can include that the subjectiverefraction includes determining a first value for an addition and/orthat the objective refraction includes determining a second value for anaddition.

The subjective refraction can include if necessary determining firstvalues for prism and base. Similarly, the objective refraction caninclude determining second values for prism and base.

The method may include that the prescription value for prism for therespective eye is set to the first value for prism for the respectiveeye. Alternatively, the prescription value for base for the respectiveeye can be set to the first value for base for the respective eye.

For example, the information about the person's vision is informationabout the person's binocular and/or monocular vision.

The wavefront measurement can be made using a wavefront sensor. Thewavefront sensor can be a Hartmann-Shack sensor.

Calculating the prescription can include determining a value forcylinder from the information about the optical properties of one orboth of the person's eyes. Calculating the prescription can includedetermining a value for cylinder axis from the information about theoptical properties of one or both of the person's eyes. Calculating theprescription can include determining a value for sphere from theinformation about the optical properties of one or both of the person'seyes. Determining the value for sphere can include determining aninitial sphere value based on the information about the person's visionand adjusting the initial sphere value based on the information aboutthe optical properties of one or both of the person's eyes.

The prescription can be calculated using an electronic processor.Outputting the prescription can include printing the prescription,displaying the prescription, or sending the prescription over anelectronic network.

The methods can include ordering eyeglass lenses based on theprescription.

The methods disclosed herein can include one or more of the followingadvantages. In some embodiments, a person's eyeglass prescription can beobtained relatively quickly compared to conventional techniques. Forexample, making a wavefront measurement can provide certain informationabout the person's eyeglass prescription more quickly than a subjectiverefraction. The wavefront measurement is a relatively quick measurement(e.g., one minute or less for both eyes) compared to a conventionalsubjective refraction (e.g., from about 10 minutes to about 30 minutesor more). Accordingly, where information is obtained using a wavefrontmeasurement in conjunction with a subjective refraction, theprescription can be obtained more quickly than using a subjectiverefraction alone. For example, in some embodiments, only binocularinformation about a person is obtained using subjective refraction,rather than both binocular and monocular information. Here, themonocular information can be obtained exclusively using a wavefrontmeasurement.

In certain embodiments, a person's eyeglass prescription can be obtainedmore accurately compared to conventional techniques. For example,obtaining information from a wavefront measurement can provide moreaccurate information about a person's eyeglass prescription compared toobtaining the information using a subjective refraction. In embodiments,eyeglass prescription accuracy can be provided to an accuracy withinabout 0.1 dpt or less (e.g., about 0.05 dpt or less, about 0.01 dpt)for, e.g., mean sphere and/or cylinder and to an accuracy within theabout 1° or less for the cylinder axis.

Prescriptions can be determined accurately with little additional inputfrom the ECP and/or with little opportunity for the ECP to introducehuman error into the eyeglass prescription. For example, theprescription can be accurately determined by a computer-implementedalgorithm that operates with minimal or no input from the ECP beyondperforming a wavefront measurement and subjective refraction.Accordingly, the opportunity for the ECP to introduce human error intothe calculation can be the same or less as conventional techniques.

In some embodiments, the procedure used to obtain a person's eyeglassprescription can provide additional information about the person'svision without performing any additional procedures. For example, awavefront measurement can be used to determine information about theperson's night vision.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features and advantages willbe apparent from the description, drawings, and claims.

DESCRIPTION OF DRAWINGS

FIG. 1A is a flow chart showing a procedure for determining an eyeglassprescription of a person and ordering lenses.

FIG. 1B is a schematic diagram of a system used to make a wavefrontmeasurement of a person's eye and to calculate an eyeglass prescriptionfor the person.

FIG. 2 is a flow chart showing a procedure for determining an eyeglassprescription of a person based on a wavefront measurement.

FIG. 3 is a flow chart showing a procedure for determining an eyeglassprescription of a person and ordering lenses.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Referring to FIG. 1A, a procedure 100 for obtaining an eyeglassprescription and ordering eyeglass lenses for a person includes makingan anamnesis 120 and medical investigation 130 of the person, followedby a subjective refraction 140 and a wavefront measurement 150. The ECPdetermines a prescription 160 based on the results of subjectiverefraction 140 and wavefront measurement 150. After the person selectseyeglass frames 170, the ECP measures a centration 180 of the frames andorders the lenses 199 from a lens maker (e.g., from a third party lensmaker or an in-house lens maker) according to the prescription 160 andcentration measurement 180.

Making anamnesis 120 typically involves questioning the person regardinghis or her medical and ocular history and any noticeable eye problems.Anamnesis 120 can include reviewing records of the person's eye carehistory. For example, in some embodiments, the anamnesis can beperformed in conjunction to reviewing a previous eyeglass prescription110.

Medical investigation 130 of a person can include determining visualacuity in each eye using the Snellen Chart, which consists of randomletters of different sizes. The letters for normal vision (20/20) are⅜-inch tall, viewed at 20 feet.

In some embodiments, medical investigation 130 include measuring theperson's eye movement and peripheral vision. These can be tested bymoving a light or object through the person's field of vision andobserving the person's response. The person's reaction to light (e.g.,pupillary response) can also be measured.

Color blindness can be tested by, for example, having the person observemulticolored dots that form numbers. Color blindness can result in theperson's inability to see certain numbers or to see a different numberthan people who are not color blind.

Medical investigation 130 can include glaucoma testing (e.g.,tonometry), which typically involves directing a puff of air at theperson's eye. The eye's response to the air puff is used to measure thepressure of the person's eyes, where abnormal readings are related toglaucoma.

Medical investigation 130 generally includes visual observation of theperson's eyes by the ECP. For example, the retina, fundus, retinalvessels, and optic nerve head can be viewed with an opthalmoscope. Dropsthat dilate the person's pupil may be used to allow more of the fundusto be viewed, although subjective refractive is generally performedprior to this dilation as these drops typically blur the person's visionfor a period of time.

Subjective refraction 140, sometimes referred to simply as a refraction,involves positioning different lenses of different strength in front ofthe person's eyes using a phoropter or a trial frame and asking theperson about their vision for the different lenses. Typically, theperson sits behind the phoropter, and looks through it at an eye chartplaced at optical infinity (e.g., 20 feet or 6 meters for distancevision), then at near (e.g., 16 inches or 40 centimeters for nearvision) for individuals needing reading glasses. The ECP then changeslenses and other settings, while asking the person for subjectivefeedback on which settings gave the best vision. Subjection refractionis typically performed on each eye separately (monocular refraction),and then on both eyes together (binocular refraction). In certainembodiments, subjective refraction is performed only on both eyestogether to provide binocular information. In such cases, the monocularinformation is determined from wavefront measurement 150.

Subjective refraction can be used to determine initial values for sphere(also referred to as mean sphere), cylinder, and/or cylinder axis forboth eyes. This information can be determined for both distance visionand near vision.

Wavefront measurement 150 can be performed using a Hartmann-Shacksensor. In such sensors, a narrow beam of radiation output from a laseror a superluminescence diode, for example, is projected onto the retinaof the person's eye through the optics of the eye. Then, radiationscattered from the retina passes through the optics, and emerges fromthe pupil. The wavefront of the emerging beam carries informationrelating to aberration errors of the optics of the eye. Then, thewavefront of the emerging beam at the exit pupil plane of the eye isrelayed (by relay optics) onto a Hartmann-Shack sensor, and output fromthe Hartmann-Shack sensor is used to measure the wavefront of theemerging beam. For an emmetropic eye, i.e., an eye without aberrationerror, the wavefront of the emerging beam is a flat surface, whereas,for an eye that produces aberration errors, the wavefront of theemerging beam is distorted from the flat surface.

A Hartmann-Shack sensor typically includes a lenslet array and a CCDcamera, which CCD camera is typically located at a focal plane of thelenslet array. Whenever a beam to be measured is projected onto theHartmann-Shack sensor, the lenslet array breaks the beam intosub-apertures, and forms a pattern of focal spots. The CCD camerarecords this pattern of focal spots, and a computer analyzes the patternof focal spots to measure the wavefront of the beam.

An exemplary system 1000 is shown in FIG. 1B. System 1000 include arelay module 1030 and a Hartman-Shack sensor 1020. Relay module 1030illuminates a person's eye 1001 with light and collects light scatteredby the retina. Relay module 1030 relays the collected light toHartmann-Shack sensor 1020, which detects the light using a detectorarray (e.g., a CCD or CMOS detector array). Hartmann-Shack sensor 1020is in communication with an electronic processor 1010 (e.g., a personalcomputer), which is configured to receive a signal from Hartmann-Shacksensor 1020 and determine the person's prescription from the signalbased on an algorithm.

Further embodiments of methods and systems for making wavefrontmeasurements of a people eyes are disclosed in the following patents:U.S. Pat. No. 6,382,795 B1, entitled “METHOD AND APPARATUS FOR MEASURINGREFRACTIVE ERRORS OF AN EYE;” U.S. Pat. No. 6,406,146 B1, entitled“WAVEFRONT REFRACTOR SIMULTANEOUSLY RECORDING TWO HARTMANN-SHACKIMAGES;” U.S. Pat. No. 6,575,572 B2, entitled “METHOD AND APPARATUS FORMEASURING OPTICAL ABERRATIONS OF AN EYE;” U.S. Pat. No. 6,997,555 B2,entitled “METHOD FOR DETERMINING VISION DEFECTS AND FOR COLLECTING DATAFOR CORRECTING VISION DEFECTS OF THE EYE BY INTERACTION OF A PATIENTWITH AN EXAMINER AND APPARATUS THEREFORE;” and U.S. Pat. No. 7,084,986B2, entitled “SYSTEM FOR MEASURING THE OPTICAL IMAGE QUALITY OF AN EYEIN A CONTACTLESS MANNER.” The entire contents of U.S. Pat. No. 6,382,795B1, U.S. Pat. No. 6,406,146 B1, U.S. Pat. No. 6,575,572 B2, U.S. Pat.No. 6,997,555 B2, and U.S. Pat. No. 7,084,986 B2 are hereby incorporatedherein by reference.

The wavefront refractor can measure a variety of different opticalerrors of the person's eyes, such as, for example, second orderaberrations, defocus, astigmatism, and higher order aberrationsincluding coma, trefoil, and spherical aberrations. These errors can bemeasured quickly (e.g., in seconds).

The person's prescription is determined based on the results ofsubjective refraction 140 and wavefront measurement 150 using analgorithm that can be implemented, for example, using a computer or anequivalent electronic processing device. In general, the algorithm canutilize data from a number of different sources to calculate theperson's prescription. For example, in certain embodiments, thealgorithm takes into account the wavefront data from both eyes, the datafrom subjective refraction 140 from both eyes, and additional data fromthe ECP. Additional data can include, for example, addition, prism,and/or base for one or both eyes, design preferences, and/or expectedlight conditions for the use one or both lenses. Another example ofadditional data is where the ECP wants the prescription to be optimizedfor a certain distance (e.g., different from infinity), this informationcan be provided so that subsequent determinations are performed based onthe distance.

In general, the person's prescription can be determined from wavefrontdata by first determining Zernike coefficients which characterize theaberrations in the person's eye. Alternatively, or additionally, theperson's prescription can be calculated from the three-dimensionalwavefront map itself. The person's prescription (e.g., sphere, cylinder,and cylinder axis) can be determined from the Zernike coefficients orfrom the three-dimensional map using a variety of methods. For example,one can calculate sphere, cylinder, and cylinder axis by fitting atorical surface to the wavefront data. Alternatively, or additionally,the Zernike coefficients or the three-dimensional wavefront map can beused to construct an image of a point source on the person's retina, andthe sphere, cylinder, and cylinder axis can be determined using an imagequality metric.

Exemplary methods are disclosed, for example, in U.S. Pat. No.6,511,180, entitled “DETERMINATION OF OCULAR REFRACTION FROM WAVEFRONTABERRATION DATA AND DESIGN OF OPTIMUM CUSTOMIZED CORRECTION,” and inEuropean Patent No. EP 1 324 689 B 1, entitled “DETERMINATION OF OCULARREFRACTION FROM WAVEFRONT ABERRATION DATA,” the entire contents both ofwhich is hereby incorporated by reference.

In some embodiments, the person's prescription is determined fromwavefront data using ray tracing techniques. For example, a ray tracingalgorithm can be used to trace a bundle of rays through the patient'seye based on the wavefront data. Sphere, cylinder, and cylinder axis,for example, can be determined from the behavior of the rays at variouslocations along their path using one or more metrics. For example, insome embodiments, the prescription is determined using a metric based oncharacteristics of the bundle of rays at and around their point ofminimum aperture (e.g., at their position of focus within the eye).These characteristics can include the cross-sectional area,cross-sectional shape, and/or longitudinal extension at this position.

FIG. 2 shows a flowchart of an exemplary embodiment of an algorithm forcalculating a person's eyeglass prescription. Initially, wavefront data(210) for each eye, provided by wavefront measurement 150, is used todetermine a wavefront refraction for each eye (220). This involves theuse of an appropriate metric on the wavefront data. The metric dependson the wavefront data, the subjective refraction (if provided) and/orthe additional data. Wavefront refraction data for each eye is used todetermine a cylinder and cylinder axis for each eye (250). The cylinderrefers to a cylindrical deviation from a spherical lens that part of aperson's prescription, usually used to correct for astigmatism. Thecylinder axis refers to the relative orientation of the cylinder foreach eye. Concurrently to determining the cylinder and cylinder axis,the mean spheres of wavefront refraction for each eye is adjusted (260)based on the wavefront refraction data, subjective refraction data 230and/or additional data 240 for each eye. For example, if ECP had toadjust the mean sphere ascertained from subjective refraction 140 forone eye, this adjustment can be emulated by adjusting the wavefrontrefractive mean sphere of the other eye by a certain amount thedifference between the mean sphere for the left eye is the same as theright eye as calculated from subjective refraction 140 is the same asthe difference calculated from wavefront refraction 150.

Once appropriate mean sphere adjustments are calculated, new mean spherevalues are determined from the adjustments (270). The adjusted meansphere values are combined with the cylinder and cylinder axiscalculated in 250 to determine the prescription for the person (280).

In general, the person's eyeglass prescription can be determined to ahigh level of accuracy using the procedures presented herein. Forexample, spherical and cylinder can be determined to within about 0.25dpt or less (e.g., about 0.1 dpt or less, about 0.05 dpt or less, 0.01dpt or less). Cylinder axis can be determined to within about ±5° orless (e.g., about ±4° or less, about ±3° or less, about ±2° or less, ±1°or less).

Referring again to FIG. 1A, as discussed previously, once the personselects eyeglass frames, the ECP performs a centration measurement 180.Centration refers to determining the horizontal distance between thecentration points of the pair of lenses. This may be specified bymonocular values, measured from the assumed centreline of the bridge ofthe nose or spectacle frame. Alternatively, if an inter-pupillarydistance is specified, this is taken to be the centration distance.

In certain embodiments, the person can select addition features for theeye glasses as indicated by 190 in the flow chart of FIG. 1A. Thesefeatures can include, for example, optional optical coatings (e.g.,antireflection coatings), bifocal lenses, and/or sun-activated tints.

After all selections have been made, the ECP orders the lenses (199)from, e.g., a third party or in-house lens maker.

Of course, while FIG. 1A shows a specific order in procedure 100, ingeneral, the order of can vary. For example, frame selection 170 andfeature selection 190 can occur at any stage in the procedure.Furthermore, in certain embodiments, the ECP can make wavefrontmeasurement 150 before making subjective refraction 140.

In some embodiments, wavefront measurement 150 can provide additionalinformation about the person's vision. For example, wavefrontmeasurement 150 can be used to provide information about the person'snight vision. Furthermore, a corneal topography measurement can be madeconcurrently to the wavefront measurement 150, in order to determineadditional information about the refractive status of the eye, which canalso be used in the calculation of the eyeglass prescription. Thetopographic information can also be used, for example, to dispensecontact lenses.

The additional information (e.g., about night vision) can be obtainedfrom the same wavefront measurement used to obtain prescriptioninformation. Accordingly, this information can be obtained withoutfurther stressing or inconveniencing the person.

In certain embodiments, certain steps in the procedure for obtaining aneyeglass prescription and ordering eyeglass lenses can be performed bypeople other than the ECP. For example, referring to FIG. 3, in aprocedure 300, rather than determining the prescription herself, the ECPsubmits the results of the wavefront measurement along with otherinformation to the lens manufacturer or laboratory (310). According to320, the lens manufacturer or laboratory then calculate the person'sprescription based on the wavefront measurement data and otherinformation from the ECP. Finally, the lenses are manufactured based onthe prescription (330). In embodiments where 320 is performed by thelens manufacturer, the manufacturer uses the prescription to make theperson's lenses. In embodiments where a laboratory calculates theprescription, the lab technician submits the prescription to the lensmanufacturer who makes the lenses.

In the following exemplarily the method as shown in FIG. 2 isdemonstrated in a stepwise manner:

1) In a first step the wavefront data for both eyes of a patient aremeasured.

2) Out of these data, in a second step the wavefront refraction, namelysphere S_WR_OD/OS, cylinder C_WR_OD/OS and axis A_WR_OD/OS as the casemay be for both eyes are calculated with an appropriate metric. Anappropriate metric can be for example the Strehl ratio of the ocularpoint spread function. In the following S is an abbreviation for sphere,C is an abbreviation for cylinder and A is an abbreviation for cylinderaxis. WR indicates wavefront refraction. OD and OS are abbreviations forOculus dexter (latin for the right eye) and Oculus Sinister (latin forthe left eye)

3) In a third step a subjective refraction for both eyes is made. As thecase may be sphere S_SR_OD/OS, cylinder C_SR_OD/OS and axis A_SR_OD/OSare determined. If needed any addition ADD_SR, prism PR_SR_OD/OS andbase BAS_SR_OD/OS; respectively, are included in the subjectiverefraction measurement.

4) The mean spheres MS_SR_OD, MS_SR_OS, MS_WR_OD, MS_WR_OS of all thetwo refractions for both eyes are calculated (sphere+half of thecylinder) in a fourth step.

5) In a fifth step a balancing of subjective and wavefront refraction isaccomplished in the following manner:

If the mean spheres MS_WR_OD/OS of the wavefront refraction is more thana predetermined value (a typical value may be 0.25 dpt) more plus thanthe mean spheres MS_SR_OD/OS of the subjective refraction (per eye),then the mean sphere MS_WR_OD/OS of the wavefront refraction will beshifted to “mean sphere of subjective refraction MS_SR_OD/OS+thispredetermined value (e.g. 0.25 dpt)”:IF MS _(—) WR _(—) OD/OS>MS _(—) SR _(—) OD/OS+0.25 dptTHEN MS _(—) WR _(—) OD/OS=MS _(—) SR _(—) OD/OS+0.25 dpt  (1)

6) If the mean spheres MS_WR OD/OS of the wavefront refraction is morethan a predetermined value LIMIT more minus than the mean spheresMS_SR_OD/OS of the subjective refraction (per eye), then the mean sphereMS_WR_OD/OS of the wavefront refraction will be shifted to “mean sphereof subjective refraction MS_WR_OD/OS−predetermined value LIMIT”.

The predetermined value LIMIT is depending on the wanted addition ADD_SR(which is the addition ADD_SR measured at the subjective refraction instep 3)) of the lens. For addition ADD_SR 0 to 1.75, the predeterminedvalue LIMIT is 0.5 dpt, for addition ADD_SR 2.00 to 2.25, thepredetermined value LIMIT is 0.25 dpt and if the addition ADD_SR isgreater than 2.25, the predetermined value LIMIT is 0. Thus, thefollowing relationships hold:IF MS _(—) WR _(—) OD/OS<MS _(—) SR _(—) OD/OS−LIMITTHEN MS _(—) WR _(—) OD/OS=MS _(—) SR _(—) OD/OS−LIMIT  (2)

wherein the LIMIT-value is determined dependent on the wanted additionADD_SR according to the following table: TABLE 1 Wanted addition ValueADD SR LIMIT 0.00 dpt to 1.75 dpt 0.50 dpt 2.00 dpt to 2.25 dpt 0.25 dptGreater 2.25 dpt 0.0 dpt

7) In a seventh step the difference D_MS_SR of the mean spheresMS_SR_OD, MS_SR_OS of the subjective refraction between the two eyes iscalculated:D _(—) MS _(—) SR=MS _(—) SR _(—) OD−MS _(—) SR _(—) OS.  (3)

8) In the following eighth step the difference D_MS_WR of the meanspheres MS_WR_OD, MS_WR_OS of the wavefront refraction between the twoeyes is calculated:D _(—) MS _(—) WR=MS WR _(—) OD−MS _(—) WR _(—) OS  (4)

9) The mean spheres MS_WR_OD/OS of the wavefront refraction of the twoeyes is now shifted in a ninth step to achieve the same differenceD_MS_WR, D_MS_SR between the two eyes than the mean spheres of thesubjective refraction MS_SR_OD/OS between the both eyes has.Change MS_WR_OD and MS_WR_OS to achieve D _(—) MS _(—) WR=D _(—) MS _(—)SR  (5)

10) Out of the new mean spheres MS_WR_OD, MS_WR_OS, the values forsphere NS_WR_OD/OS of the prescription and the cylinder C_WR_OD/OS arecalculated for both eyes.

11) If the subjective refraction shows any need of an addition, thismeasured addition ADD_SR has to be shifted, depending on the differenceD _(—) MS=(MS _(—) SR OD+MS _(—) SR OS)/2−(WR _(—) OD−MS _(—) WR _(—)OS)/2  (6)according to the following equation:N_ADD=ADD_(—) SR+ADD_SHIFT  (7)

whereby the value ADD_SHIFT has to be extracted from the followingtable: TABLE 2 addition from subjective mean sphere Predeterminedrefraction difference shift value ADD_SR D_MS ADD_SHIFT 0.00 dpt +0.25dpt to −0.50 dpt 0.00 dpt 0.75 dpt to 1.75 dpt +0.25 dpt to +0.12 dpt−0.25 dpt +0.13 dpt to −0.12 dpt 0.00 dpt −0.13 dpt to −0.37 dpt +0.25dpt −0.38 dpt to −0.50 dpt +0.50 dpt 2.00 dpt to 2.25 dpt +0.25 dpt to+0.12 dpt −0.25 dpt +0.13 dpt to −0.12 dpt 0.00 dpt −0.13 dpt to −0.25dpt +0.25 dpt Greater 2.25 dpt 0.00 dpt 0.00 dpt

12) The final prescription consists of the new sphere NS_WR_OD/OS, thecylinder of the wavefront refraction C_WR_OD/OS, the axis of thewavefront refraction A_WR_OD/OS and if needed the additional parametersaddition N_ADD, prism PR_SR_OD/OS, and base BAS_SR_OD/OS

The exemplary method described above may be summarized as follows:

i) The mean spheres of the wavefront refraction is limited to the meanspheres of the subjective refraction; steps 1) to 6)

ii) The spheres of the wavefront refraction is shifted to achieve thebalancing of the subjective refraction; steps 7) to 10)

iii) The addition is adjusted if needed; step 11)

iv) Cylinder and axis are taken from the wavefront refraction withoutany changes; step 12). In certain embodiments, the cylinder and the axismight be changed.

v) Prism and Base were taken from the subjective refraction without anychanges; step 12). In some embodiments, the prism and the base might bechanged.

The foregoing provides certain illustrative embodiments. Otherembodiments are in the claims.

1. A method, comprising: making a subjective refraction of a person to determine information about the person's vision; making an objective refraction of the person to determine information about the person's vision; calculating a prescription for the person based on the information about the person's vision determined by the subjective refraction and the objective refraction; and outputting the prescription.
 2. The method of claim 1, wherein the objective refraction is derived from a wavefront measurement of one or both of the person's eyes determining information about the optical properties of the one or both of the person's eyes.
 3. The method of claim 1, wherein the objective refraction is derived from a ray tracing method of one or both of the person's eyes determining information about the optical properties of the one or both of the person's eyes.
 4. The method of claim 1, wherein the objective refraction is derived from a tomographic method of one or both of the person's eyes determining information about the optical properties of the one or both of the person's eyes.
 5. The method of claim 1, wherein the objective refraction is derived from a Tscherning method of one or both of the person's eyes determining information about the optical properties of the one or both of the person's eyes.
 6. The method of claim 1, wherein the subjective refraction comprises determining a first value for sphere of one or both of the person's eyes and/or wherein the objective refraction comprises determining a second value for sphere of the one or both of the person's eyes and wherein calculating the prescription comprises determining a prescription value for sphere of one or both of the person's eyes from the first value for sphere of one or both of the person's eyes and the second value for sphere of one or both of the person's eyes.
 7. The method of one of claim 1, wherein the subjective refraction comprises determining a first value for cylinder of one or both of the person's eyes and/or wherein the objective refraction comprises determining a second value for cylinder of one or both of the person's eyes and wherein calculating the prescription comprises determining a prescription value for cylinder of one or both of the person's eyes from the first value for cylinder of one or both of the person's eyes and/or the second value for cylinder of one or both of the person's eyes.
 8. The method of one of claim 1, wherein the subjective refraction comprises determining a first value for cylinder axis of one or both of the person's eyes and/or wherein the objective refraction comprises determining a second value for cylinder axis of one or both of the person's eyes and wherein calculating the prescription comprises determining a prescription value for cylinder axis of one or both of the person's eyes from the first value for cylinder axis of one or both of the person's eyes and/or the second value for cylinder axis of one or both of the person's eyes.
 9. The method of one of claim 7, wherein calculating the prescription comprises determining a prescription value for mean sphere of one or both of the person's eyes from a first value for mean sphere of one or both of the person's eyes as calculated from the sum of the first value for sphere and half of the first value for cylinder and a second initial value for mean sphere of one or both of the person's eyes as calculated from the sum of the second value for sphere and half of the second value for cylinder.
 10. The method of claim 9, wherein a second value for mean sphere of one or both of the person's eyes is set to the sum of the second initial value for mean sphere for the respective eye and a predetermined plus value if the second initial value for mean sphere for the respective eye exceeds the predetermined plus value and wherein the second value for mean sphere for the respective eye is set to the difference of the second initial value for mean sphere for the respective eye and a predetermined minus value if the second initial value for mean sphere for the respective eye exceeds the predetermined minus value and wherein the difference of the first mean spheres between the two eyes is calculated and wherein the difference of the second mean spheres between the two eyes is calculated and wherein the second mean spheres of the respective eyes are amended such that the differences between the first and second mean spheres of the respective two eyes are identical and wherein the prescription value for mean sphere of the respective eye is set to the amended second mean sphere.
 11. The method according to claim 10, wherein the predetermined plus value is 0.25 dpt.
 12. The method according to one of claim 10, wherein the predetermined minus value is set to: 0.50 dpt for a wanted addition between 0.00 dpt and 1.75 dpt; 0.25 dpt for a wanted addition between 2.00 dpt and 2.25 dpt; or 0.00 dpt for a wanted addition greater than 2.25 dpt.
 13. The method according to one of claim 7, wherein the prescription value for cylinder of the respective eye is set to the first value for cylinder of the respective eye.
 14. The method according to one of claim 7, wherein the prescription value for cylinder axis of the respective eye is set to the first value for cylinder axis of the respective eye.
 15. The method of one of claim 1, wherein the subjective refraction comprises determining a first value for an addition and/or wherein the objective refraction comprises determining a second value for an addition.
 16. The method of claim 14, wherein the prescription value for addition is set to: 0.00 dpt if the difference of half of the sum of the first mean spheres of both eyes and half of the difference between the second mean spheres of both eyes is in the range of 0.25 dpt±0.15 dpt and −0.5 dpt±0.15 dpt and if the first value for an addition is 0 dpt±0.15 dpt; the first value for an addition −0.25 dpt±0.15 dpt if the difference of half of the sum of the first mean spheres of both eyes and half of the difference between the second mean spheres of both eyes is in the range of +0.25 dpt±0.02 dpt and +0.12 dpt±0.02 dpt and if the first value for an addition is in the range between 0.75 dpt±0.15 dpt and 1.75 dpt±0.15 dpt; the first value for an addition ±0.15 dpt if the difference of half of the sum of the first mean spheres of both eyes and half of the difference between the second mean spheres of both eyes is in the range of +0.13 dpt±0.02 dpt and −0.12 dpt±0.02 dpt and if the first value for an addition is in the range between 0.75 dpt±0.15 dpt and 1.75 dpt±0.15 dpt; the first value for an addition +0.25 dpt±0.15 dpt if the difference of half of the sum of the first mean spheres of both eyes and half of the difference between the second mean spheres of both eyes is in the range of −0.13 dpt±0.02 dpt and −0.37 dpt±0.02 dpt and if the first value for an addition is in the range between 0.75 dpt±0.15 dpt and 1.75 dpt±0.15 dpt; the first value for an addition +0.50 dpt±0.15 dpt if the difference of half of the sum of the first mean spheres of both eyes and half of the difference between the second mean spheres of both eyes is in the range of −0.38 dpt±0.02 dpt and −0.5 dpt±0.02 dpt and if the first value for an addition is in the range between 0.75 dpt±0.15 dpt and 1.75 dpt±0.15 dpt; the first value for an addition −0.25 dpt±0.15 dpt if the difference of half of the sum of the first mean spheres of both eyes and half of the difference between the second mean spheres of both eyes is in the range of +0.25 dpt±0.02 dpt and +0.12 dpt±0.02 dpt and if the first value for an addition is in the range between 2.00 dpt±0.15 dpt and 2.25 dpt±0.15 dpt; the first value for an addition ±0.15 dpt if the difference of half of the sum of the first mean spheres of both eyes and half of the difference between the second mean spheres of both eyes is in the range of +0.13 dpt±0.02 dpt and −0.12 dpt±0.02 dpt and if the first value for an addition is in the range between 2.00 dpt±0.15 dpt and 2.25 dpt±0.15 dpt; the first value for an addition +0.25 dpt±0.15 dpt if the difference of half of the sum of the first mean spheres of both eyes and half of the difference between the second mean spheres of both eyes is in the range of −0.13 dpt±0.02 dpt and −0.25 dpt±0.02 dpt and if the first value for an addition is in the range between 2.00 dpt±0.15 dpt and 2.25 dpt±0.15 dpt; or the first value for an addition ±0.15 dpt if the first value for an addition is greater than 2.25 dpt±0.15 dpt.
 17. The method of one of claim 1, wherein the subjective refraction comprises determining first values for prism and base and/or wherein the objective refraction comprises determining second values for prism and base.
 18. The method of claim 17, wherein the prescription value for prism for the respective eye is set to the first value for prism for the respective eye and/or the prescription value for base for the respective eye is set to the first value for base for the respective eye.
 19. A system, comprising: an input interface configured to input information about a person's vision determined on the basis of a subjective refraction; a device configured to get information about a person's vision determined on the basis of an objective refraction; a calculating device configured to calculate a prescription for the person based on the information about the person's vision determined by subjective refraction and based on the information about the person's vision determined by objective refraction; and an outputting interface configured to output the prescription.
 20. A method, comprising: making a subjective refraction of a person to determine information about the person's vision; making a wavefront measurement of one or both of the person's eyes to determine information about the optical properties of one or both of the person's eyes; calculating a prescription for the person based on the information about the person's vision and the information about the optical properties of one or both of the person's eyes; and outputting the prescription.
 21. The method of claim 20, wherein the information about the person's vision is information about the person's binocular vision.
 22. The method of one of claim 20, wherein the wavefront measurement is made using a wavefront sensor.
 23. The method of claim 22, wherein the wavefront sensor is a Hartmann-Shack sensor.
 24. The method of one of claim 20, wherein calculating the prescription comprises determining a value for cylinder from the information about the optical properties of one or both of the person's eyes.
 25. The method of one of claim 20, wherein calculating the prescription comprises determining a value for cylinder axis from the information about the optical properties of one or both of the person's eyes.
 26. The method of one of claim 20, wherein calculating the prescription comprises determining a value for sphere from the information about the optical properties of one or both of the person's eyes.
 27. The method of claim 26, wherein determining the sphere value comprises determining an initial sphere value based on the information about the person's vision and adjusting the initial sphere value based on the information about the optical properties of one or both of the person's eyes.
 28. The method of one of claim 20, wherein the prescription is calculated using an electronic processor.
 29. The method of one of claim 20, wherein outputting the prescription comprises printing the prescription, displaying the prescription, or sending the prescription over an electronic network.
 30. The method of one of claim 20, further comprising ordering eyeglass lenses based on the prescription.
 31. A method, comprising: making a wavefront measurement of one or both of the person's eyes to determine information about the optical properties of one or both of the person's eyes; calculating a prescription for the person based on the information about the optical properties of one or both of the person's eyes, wherein calculating the prescription comprises ray tracing light paths through one or both of the person's eyes based on the information about the optical properties of one or both of the person's eyes; and outputting the prescription.
 32. A system, comprising: relay optics configured to collect illumination scattered from a person's eye during operation of the system; an optical sensor configured to detect the illumination collected by the relay optics; and and electronic processor configured to receive information about the illumination detected by the optical sensor and to calculate a prescription for the person based on the information, wherein calculating the prescription comprises ray tracing light paths through the person's eye based on the information.
 33. A method, comprising: calculating a prescription for the person based on the information about a person's vision determined by a subjective refraction and an objective refraction.
 34. The method of claim 33, further comprising making the subjective refraction of the person to determine information about the person's vision.
 35. The method of claim 34, further comprising making the objective refraction of the person to determine information about the person's vision.
 36. The method of claim 33, further comprising outputting the prescription.
 37. A system, comprising: a device configured to calculate a prescription for a person based on information about the person's vision determined by subjective refraction and based on information about the person's vision determined by objective refraction; and an outputting interface configured to output the prescription. 